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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 3.X/CPM 3.0/Y2K PATCHES/SORT.PLM
Sepp J Morris 31738079c4 Upload
Digital Research
2020-11-06 18:50:37 +01:00

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$title ('SDIR - Sort Module')
sort:
do;
/* sort module for extended dir */
$include(comlit.lit)
print: procedure(str$adr) external; /* in util.plm */
dcl str$adr address;
end print;
dcl sorted boolean public; /* set by this module if successful sort */
$include(finfo.lit)
declare
buf$fcb$adr address external, /* index into directory buffer */
buf$fcb based buf$fcb$adr (32) byte,
/* fcb template for dir */
(f$i$adr, first$f$i$adr, last$f$i$adr, x$i$adr, filesfound)
address external,
/* indices into file$info array */
file$info based f$i$adr f$info$structure,
mid$adr address,
mid$file$info based mid$adr f$info$structure;
mult23: procedure(index) address public;
dcl index address; /* return address of file$info numbered by index */
return shl(index, 4) + shl(index,2) + shl(index,1) + index + first$f$i$adr;
/* index * size(file$info) + base of file$info array */
end mult23;
lessthan: procedure( str1$adr, str2$adr) boolean;
dcl (i,c1,c2) byte, /* true if str1 < str2 */
(str1$adr, str2$adr) address, /* sorting on name and type field */
str1 based str1$adr (1) byte, /* only, assumed to be first in */
str2 based str2$adr (1) byte; /* file$info record */
do i = 1 to 11;
if (c1:=(str1(i) and 7fh)) <> (c2:=(str2(i) and 7fh)) then
return(c1 < c2);
end;
return(false);
end lessthan;
dcl f$i$indices$base address public,
f$i$indices based f$i$indices$base (1) address;
qsort: procedure(l,r); /* no recursive quick sort, sorting largest */
dcl (l,r,i,j,temp) address,/* partition first */
stacksiz lit '14', /* should always be able to sort 2 ** stacksiz */
stack (stack$siz) structure (l address, r address),
sp byte;
sp = 0; stack(0).l = l; stack(0).r = r;
do while sp < stack$siz - 1;
l = stack(sp).l; r = stack(sp).r; sp = sp - 1;
do while l < r;
i = l; j = r;
mid$adr = mult23(f$i$indices(shr(l+r,1)));
do while i <= j;
f$i$adr = mult23(f$i$indices(i));
do while lessthan(f$i$adr,mid$adr);
i = i + 1;
f$i$adr = mult23(f$i$indices(i));
end;
f$i$adr = mult23(f$i$indices(j));
do while lessthan(mid$adr,f$i$adr);
j = j - 1;
f$i$adr = mult23(f$i$indices(j));
end;
if i <= j then
do; temp = f$i$indices(i); f$i$indices(i) = f$i$indices(j);
f$i$indices(j) = temp;
i = i + 1;
if j > 0 then j = j - 1;
end;
end; /* while i <= j */
if j - l < r - i then /* which partition is larger */
do; if i < r then
do; sp = sp + 1; stack(sp).l = i; stack(sp).r = r;
end;
r = j; /* continue sorting left partition */
end;
else
do; if l < j then
do; sp = sp + 1; stack(sp).l = l; stack(sp).r = j;
end;
l = i; /* continue sorting right partition */
end;
end; /* while l < r */
end; /* while sp < stack$siz - 1 */
if sp <> 255 then
call print(.(cr,lf,lf,'Sort Stack Overflow',cr,lf,'$'));
else sorted = true;
end qsort;
sort: procedure public;
dcl i address;
f$i$indices$base = last$f$i$adr + size(file$info);
if filesfound < 2 then
return;
if shr((x$i$adr - f$i$indices$base),1) < filesfound then
do;
call print(.('Not Enough Memory for Sort',cr,lf,'$'));
return;
end;
do i = 0 to filesfound - 1;
f$i$indices(i) = i; /* initialize f$i$indices */
end;
call print(.(cr,lf,'Sorting Directory...',cr,lf,'$'));
call qsort(0,filesfound - 1);
sorted = true;
end sort;
end sort;